Survey and Pathogenicity of Fusarium avenaceum Causing Crown Rot and Head Blight on Small-Grain Cereals

Abstract

Survey-based investigations were conducted to determine the occurrence, distribution, and pathogenic potential of Fusarium avenaceum associated with crown rot and head blight symptoms in small-grain cereals. Field assessments across major cereal-growing regions revealed characteristic disease symptoms including crown discoloration, root decay, premature senescence, and bleached spikelets with partial or complete head sterility. Fungal isolates obtained from symptomatic crown and spike tissues were cultured and identified based on morphological traits, including cottony mycelial growth, production of slender macroconidia, and abundant microconidia consistent with Fusarium species. Pathogenicity tests conducted on susceptible wheat and barley cultivars under controlled conditions successfully reproduced crown rot and head blight symptoms, confirming the virulence of the isolates and fulfilling Koch’s postulates. Molecular identification using ITS rDNA, TEF1-α, and RPB2 gene sequencing confirmed isolates as F. avenaceum, showing high similarity with reference sequences from global databases. Phylogenetic analysis placed all isolates within a well-supported clade of the Fusarium avenaceum species group, indicating limited but detectable genetic variability among populations from different locations. Disease severity was strongly associated with cool and moist environmental conditions, particularly during flowering stages, which favored infection and systemic colonization. The study highlights the dual role of F. avenaceum in causing both crown rot and head blight, emphasizing its epidemiological importance in small-grain cereal production systems. These findings underscore the need for integrated disease management strategies, including crop rotation, resistant cultivars, and timely fungicide applications to reduce yield losses and improve cereal crop health under variable agro-climatic conditions.